1. Field of the Invention
The present invention relates to a scrubber for removing soluble materials from toxic gases, and more particularly to a scrubber for removing soluble materials from harmful gaseous effluents with high efficiency and safety.
2. Description of the Related Art
Semiconductor manufacturing facilities utilize chemical vapor deposition, etching and a wide variety of other unit operations in the fabrication of modern semiconductor devices using process gases such as SF6, SiCl4, SiH2Cl2, and WF6. The gaseous effluent from processing units in such facilities comprise the unconsumed process gases, as well as by-products of such gases. The gaseous effluent additionally may contain significant quantities of particulates such as silica, which must be removed, in addition to various water soluble components such as hydrochloric acid and residuals of phosphine and arsine.
Water scrubbing is commonly used to remove such particulates and water-soluble gases from the process effluent stream. In such scrubbing, the effluent gas is intimately contacted with water, e.g., by passage of the gaseous effluent through a water spray, to dissolve the soluble gas components and wet and thereby remove the particulates. The scrubbing liquid may then be filtered to remove the scrubbed particulates from the scrubbing medium. The water scrubber unit typically is deployed immediately upstream of a bulk exhaust for the entire plant facility, and is used to treat the process facility effluent, which may vary considerably in concentration of water-soluble components and particulates, depending on the specific types of semiconductor devices or subassembly parts which are being manufactured, and the resulting xe2x80x9cmixxe2x80x9d of unit operations being carried out in the process facility.
FIG. 1A shows a conventional fume scrubber 100. As shown in FIG. 1A, a scrubbing chamber 110 having a filter region 120 therein is shown. The filter region 120 comprises an upper perforate diverter plate 122 and a lower perforate plate 124. A plurality of filter media 126 are packed into the filter region 120 and between the perforate diverter plate 122 and the perforate plate 124. The detail structure of the filter media 126 is shown in FIG. 1B and the filter media 126 is comprised of plastic packing spheroids formed of open annular loops as shown in the figure. In the top of the scrubbing chamber 110, there are a gas inlet 112a, an opening 112b, fluid inlets 114a and 114b. A dry exhaust pump 152 exhausts the gaseous effluent from processing units to the scrubbing chamber 110 through a gas exhaust conduit 132 connecting the gas inlet 112a. An N2 purge conduit 133 is connected to the gas exhaust conduit 132. A gas discharge conduit 134 connecting to a main gas discharge conduit (not shown) is through the top of the scrubbing chamber 110 and the filter region 120 by the opening 112b. The gas discharge conduit 134 has a gas inlet 135 with a tilt opening under the perforate plate 124. A tap water supply pipe 136 connects the scrubbing chamber 110 by the fluid inlets 114a. There are also a fluid outlet 116a and an opening 116b on the bottom of the scrubbing chamber 110 as shown in FIG. 1A. A recirculation pump 154 exhausts the scrubbing water from the bottom of the scrubbing chamber 110 back to the filter region 120 via a recirculation pipe 138. The two ends of the recirculation pipe 138 individually connect the scrubbing chamber 110 at the fluid inlets 114b and the fluid outlet 116a. An over flow drain pipe 140 used to drain excess scrubbing water is disposed through the bottom of the scrubbing chamber 110 by the opening 116b, and the over flow drain pipe 140 has a fluid outlet 142 used to drain the excess scrubbing water.
In the operation of the conventional fume scrubber 100, the gaseous effluent from processing units is exhausted through the gas exhaust conduit 132 into the scrubbing chamber 110 by the dry exhaust pump 152, wherein the N2 purge conduit 133 provides dry N2 gas to exclude moisture so that less contamination or clump of particulates will precipitate. The gaseous effluent passes the filter region 120 and contacts with the tap water from the tap water supply pipe 136, and the water-soluble gas components will solve in the tap water. Owing to the open annular loops of the filter media 126, the water-soluble gas components will solve in the tap water flowing along the open annular loops more effectively. After contacting and adsorbing the gas components, the tap water transfers to scrubbing water and flows to the bottom of the scrubbing chamber 110. The scrubbing water accumulates at the bottom of the scrubbing chamber 110 until the scrubbing water surface reaches the fluid outlet 142, and the excess scrubbing water will be drain through the over flow drain pipe 140 to a main drain pipe which is not shown in FIG. 1A. The scrubbing water also will be exhausted through the recirculation pipe 138 back to the filter region 120 by the recirculation pump 154. The scrubbing water will remix with the gaseous effluent through the recirculation cycle set forth. After passing the filter region 120 and mixing with the tap water and the scrubbing water, the gaseous effluent will be exhausted through the gas discharge conduit 134 to the main gas discharge conduit (not shown).
However, it is found that the drawbacks of the conventional fume scrubber 100 present environment protection issues and production facility malfunctions, and even result in factory safety problems. For example, the scrubbing water is usually exhausted together with the gaseous effluent through the gas discharge conduit 134 to the main gas discharge conduit (not shown) after passing the filter region 120 thereby results in the pump malfunctions of the production facilities connected to the main gas discharge conduit and even causes serious factory safety problems. Furthermore, the mixing efficiency of the gaseous effluent with the tap water and the scrubbing water is not satisfactory and the environment protection issues will arise from the interruption of the tap water, and thus the production facilities must be shut down. In view of the drawbacks mentioned above, it is desirable to provide an advance scrubber that can prevent the problems of the conventional fume scrubber set forth, it is toward these goals that this invention specially directs.
It is therefore an object of the invention to provide an advance scrubber having high recirculation efficiency of the harmful gaseous effluent.
It is another object of this invention to provide an advance scrubber which can meet the standards of environment protection and the requirements of factory safety.
It is a further object of this invention to provide a reliable scrubber for removing soluble materials from harmful gaseous effluents with high efficiency and safety.
It is another object of this invention to provide an advance scrubber which renders the production facilities or processing units continually operating as the supply of the scrubbing liquid terminates.
To achieve these objects, and in accordance with the purpose of the invention, a scrubber of the invention for scrubbing gaseous effluents by a scrubbing liquid is provided. The scrubber comprises a scrubbing chamber, a first gas conduit connecting the top of the scrubbing chamber, a manual valve, a second gas conduit connecting the first gas conduit by the manual valve, a gas exhaust pump exhausting a gaseous effluent to the second gas conduit, a check valve, a third gas conduit having a purge conduit used to transit a purge gas, the third gas conduit connecting the second gas conduit by the check valve, the third gas conduit connecting the bottom of the scrubbing chamber to transit the gaseous effluent into the scrubbing chamber, wherein only effluents from the second gas conduit to the third gas conduit can pass said check valve, a scrubbing liquid supply pipe used to transit a scrubbing liquid into the scrubbing chamber connecting the top of the scrubbing chamber, a recirculation pump used to exhaust the scrubbing liquid connecting the bottom of the scrubbing chamber, a recirculation pipe used to recirculate the scrubbing liquid connecting said recirculation pump and the top of the scrubbing chamber, and a scrubbing liquid drain pipe connecting the scrubbing chamber at a level higher than the perforate plates. The scrubbing chamber further comprises a filter region therein and at least two perforate plates disposed in sequence and under the perforate filter. The filter region comprises a perforate diverter, a perforate filter under the perforate diverter and a plurality of filter media packed between the perforate diverter and the perforate filter.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.